Chip-type LED and method for manufacturing the same

ABSTRACT

In a chip-type LED according to an embodiment of the present invention, a first recess hole for mounting an LED chip and a second recess hole for connecting a fine metal wire are formed in an insulating substrate, a metal sheet serving as a first wiring pattern is formed at a portion that includes the first recess hole, a metal sheet serving as a second wiring pattern is formed at a portion that includes the second recess hole, an LED chip is mounted on the metal sheet within the first recess hole, the LED chip is electrically connected to the metal sheet within the second recess hole via a fine metal wire, the LED chip including the first recess hole and the fine metal wire including the second recess hole are encapsulated in a first transparent resin that contains a fluorescent material, a surface of the insulating substrate including the first transparent resin is encapsulated in a second transparent resin.

BACKGROUND OF THE INVENTION

This application claims priority under 35 U.S.C. §119(a) on JapanesePatent Application No. 2007-284136 filed in Japan on Oct. 31, 2007 andJapanese Patent Application No. 2007-332943 filed in Japan on Dec. 25,2007, the entire contents of which are herein incorporated by reference.

The present invention relates to a surface-mounted chip-type LED and amethod for manufacturing the same, and is used as a light source invarious types of display panels, backlighting for liquid-crystal displayapparatuses, lighting switches, and the like.

Chip-type LEDs have conventionally been used as a light source invarious types of display panels, backlighting for liquid-crystal displayapparatuses, lighting switches, and the like.

FIG. 12 shows an example of the structure of a conventional chip-typeLED.

The conventional chip-type LED has a two-layer structure includinginsulating substrates 81 and 82, and is configured such that a throughhole 83 is formed in the upper insulating substrate 82, a wiring pattern84 is formed such that it extends to the bottom within the through hole83 (i.e., the upper surface of the lower insulating substrate 81), anLED chip 85 is mounted on the wiring pattern 84 within the through hole83, the LED chip 85 is connected to another wiring pattern 86 with afine metal wire (Au wire, etc.) 87, and the surface of the insulatingsubstrate 82 is encapsulated in a transparent resin 88 so as to includethe LED chip 85 and the fine metal wire 87. Chip-type LEDs having astructure as described above are disclosed in, for example, JP2001-160629A and JP 2006-190764A.

However, a chip-type LED of the conventional structure requires twoinsulating substrates 81 and 82, and the lower insulating substrate 82is required to have a minimum thickness necessary to carry the LED chip85 because the LED chip 85 is mounted on the lower insulating substrate82, and thus problems exist such as difficulties achieving a thin LEDand high costs.

In order to solve this problem, JP H07-235696A discloses a wiringstructure for a semiconductor device and a method for forming the same.According to JP H07-235696A, a semiconductor device is obtained byforming a through hole on the surface side of an overall thincopper-laminated substrate obtained by laminating thin copper plates onthe surface and undersurface of an insulating resin substrate, mountingan LED chip on an exposed surface of the lower copper plate inside thethorough hole, and performing encapsulation with a single resin layer soas to cover the through hole.

JP H07-235696A that discloses this thin semiconductor device doesn'treveal a technique for letting the semiconductor device to emit whitelight. In order to cause the semiconductor device to emit white light,it is only necessary to include a yellow fluorescent material in thesingle resin layer. To form the encapsulating resin, there is a methodin which a fluorescent material is included in a semi-cured tablet resin(a resin for transfer molding) and transfer molding is performed toobtain a white light-emitting chip LED. This method provides very goodworkability and thus is suitable for mass production.

However, due to the nature of transfer molding, the concentration of thefluorescent material varies significantly from place to place, and it isimpossible to avoid variations in chromaticity, which is a veryimportant property of white light-emitting LEDs.

In addition, there is a limitation on the production method of such atable resin (the quantity produced at one time is very large), so theblending ratio of the fluorescent material cannot be flexibly changed.

Moreover, it is generally known that the light emitting efficiency canbe increased to a maximum by disposing the fluorescent material near theLED chip. When transfer molding is performed, however, the fluorescentmaterial spreads not only near the LED chip but also throughout theentire molding resin, making the light emitting efficiency low relativeto the amount of the fluorescent material used. Also, colornonuniformity is likely to occur due to sedimentation of the fluorescentmaterial and the like.

Silicone resins having a high heat resistance are commonly used as anencapsulating resin material, but it is impossible to perform transfermolding with a silicone resin because transfer molding employs a resinthat can be in a semi-cured state. It is possible to perform transfermolding with a resin that is liquid in an uncured state such as siliconeresin, but a highly sophisticated technique is required because airbubbles are easily included in a low viscous liquid resin and adedicated apparatus is necessary that includes a means for preventingthe inclusion of air bubbles.

Furthermore, silicone resins have a rigidity lower than that of epoxyresins, and in a chip-type LED structure in which a member forprotecting the encapsulating resin, such as a reflective material, isnot provided around the encapsulating resin, the encapsulating resin iseasily scratched and deformed (e.g., due to direct contact of the uppersurface with a mounting device). For this reason, silicone resins arenot suitable for use as an encapsulating resin.

Nonetheless, the resin near the chip is degraded significantly by light(ultraviolet, near-ultraviolet to blue light) emitted from the chipbefore conversion by the fluorescent material. Accordingly, a siliconeresin, which has better light resistance than an epoxy resin, should beused to encapsulate the periphery of the chip.

SUMMARY OF THE INVENTION

The present invention has been conceived to solve the aforementionedproblems, and it is an object of the present invention to provide a thinchip-type LED, in which an LED chip is mounted within a through holeformed in a substrate, that can suppress sedimentation and unevendistribution of the fluorescent material and emit white light or visiblelight with less color nonuniformity, and a method for manufacturing sucha chip-type LED.

In order to solve the above problems, the present invention relates to achip-type LED, wherein a first recess hole for mounting an LED chip anda second recess hole for connecting a fine metal wire are formed in aninsulating substrate, a metal sheet serving as a first wiring pattern isformed at a portion that includes the first recess hole, a metal sheetserving as a second wiring pattern is formed at a portion that includesthe second recess hole, an LED chip is mounted on the metal sheet withinthe first recess hole, the LED chip is electrically connected to themetal sheet within the second recess hole via a fine metal wire, the LEDchip including the first recess hole and the fine metal wire includingthe second recess hole are encapsulated in a first transparent resinthat contains a fluorescent material, a surface of the insulatingsubstrate including the first transparent resin is encapsulated in asecond transparent resin. In accordance with this configuration, anencapsulation with the first transparent resin may be performed by aprocess different from that with the second transparent resin.

Another aspect of the present invention relates to a chip-type LED,wherein a first recess hole for mounting an LED chip and a second recesshole for connecting a fine metal wire are formed in an insulatingsubstrate, a metal sheet serving as a first wiring pattern is formed ata portion that includes the first recess hole, a metal sheet serving asa second wiring pattern is formed at a portion that includes the secondrecess hole, an LED chip is mounted on the metal sheet within the firstrecess hole, the LED chip is electrically connected to the metal sheetwithin the second recess hole via a fine metal wire, the LED chipincluding the first recess hole and part of the fine metal wire areencapsulated in a first transparent resin that contains a fluorescentmaterial, the second recess hole and another part of the fine metal wireare encapsulated in a third transparent resin, a surface of theinsulating substrate including the first transparent resin and the thirdtransparent resin is encapsulated in a second transparent resin. Inaccordance with this configuration, an encapsulation with the first andthird transparent resins may be performed by a process different fromthat with the second transparent resin.

With this configuration, the area on which the LED chip is mounted andthe area to which an end of the fine metal wire, the other end of whichis connected to the LED chip, is connected are formed on the metalsheets, whereby it is possible to lower the height of the fine metalwire. Furthermore, because the LED chip is mounted directly on the metalsheet (first wiring pattern), it is unnecessary to use a conventionalsubstrate and possible to reduce the thickness. Accordingly, the heightof the fine metal wire can be made lower than that of conventionaltechnology, making the chip-type LED even thinner.

In the present invention, the first wiring pattern on which the LED chipis mounted and the second wiring pattern to which an end of the finemetal wire is connected can be electrically insulated easily by removingthe metal sheet. Furthermore, because the wiring pattern formed withinthe recess holes is electrically connected directly to the metal sheetat the bottom, it is unnecessary to form a wiring pattern and the likein the outer periphery of the insulating substrate, which makes themanufacturing method easier than the method for manufacturing aconventional chip-type LED. Accordingly, the manufacturing cost can bereduced as well.

In this case, the bottom of the first recess hole on which the LED chipis mounted and the bottom of the second recess hole to which the finemetal wire extending from the LED chip is electrically connected areformed to have a substantially equal height. This eliminates the need toadjust the laser output when processing, etc., making the recess holeforming process easy.

In the present invention, the second recess hole to which the fine metalwire extending from the LED chip is electrically connected may be formedat at least two locations. By forming the second recess hole at at leasttwo locations, even when the LED chip has an electrode structure inwhich anode and cathode electrodes are formed on the surface side, andmore complicated wiring is employed that uses fine metal wires insteadof drawing out the electrodes of the LED chip from the mounting surfaceof the LED chip, the chip-type LED can be made thinner.

The chip-type LED of the present invention may have a structure in whicha groove in which the fine metal wire is provided is formed on thesurface of a wall member provided between the first recess hole and thesecond recess hole. By forming the groove as described and providing thefine metal wire such that the fine metal wire passes through the groove,the height at which the fine metal wire is disposed can be lowered evenmore, making the chip-type LED even thinner.

In the present invention, a fluorescent material may be contained in thetransparent resin. Furthermore, it is preferable that the inner surfacesof the recess holes are formed to have inclined surfaces that flaregradually from the undersurface toward the surface of the insulatingsubstrate. With this configuration, when the chip-type LED of thepresent invention is used as a light source in various types of displaypanels, backlighting for liquid-crystal display apparatuses, lightingswitches and the like, the light that travels toward the side faces whenthe chip-type LED lights up is reflected by the inclined surfaces andtravels upward, and therefore the reflective efficiency in the upwarddirection can be improved.

It is preferable that the first transparent resin is a silicone-basedresin, and the second transparent resin is an epoxy-based resin. Byusing a silicone-based resin as the first transparent resin, the thermalstress is reduced, and the occurrence of a disconnection defect betweenthe LED chip and the fine metal wire as well as between the metalsurface of the second recess hole for connecting a fine metal wire andthe fine metal wire is reduced. It is preferable that the firsttransparent resin that has been formed to cover the LED chip, the finemetal wire and the second recess hole serving as a fine metal wireconnecting portion is covered with an epoxy-based resin as the secondtransparent resin. The epoxy-based resin is superior in viscosity,transparency, weather resistance and strength, and is suitable as anencapsulating resin.

Furthermore, by forming the third transparent resin using asilicone-based resin, the occurrence of a disconnection defect of theconnecting portion of the fine metal wire can be reduced becausesilicone-based resins have a small thermal expansion coefficient.Moreover, because different encapsulating resins can be used for thefirst recess hole for mounting an LED chip, the second recess hole forconnecting a fine metal wire and other regions of the insulatingsubstrate surface, it is possible to form a package structure that canprovide a great freedom in selection of resins.

The present invention further relates to a method for manufacturing achip-type LED including: a step of forming metal sheets on the surfaceand the undersurface of an insulating substrate; a step of removing themetal sheet on the surface side of the insulating substrate at an LEDchip mounting position and a fine metal wire connecting position; a stepof forming a first recess hole and a second recess hole in the regionsfrom which the metal sheet has been removed such that the first andsecond recess holes have a depth extending to the metal sheet on theundersurface side of the insulating substrate; a step of forming aconductive layer such that a conductive layer extends over the sidefaces of the recess holes and the metal sheet at the bottom of therecess holes; a step of forming an Au-containing layer on the surface ofthe conductive layer by vapor deposition; a step of forming aninsulating region; a step of mounting an LED chip on the bottom of thefirst recess hole; a step of electrically connecting the LED chip andthe bottom of the second recess hole using a fine metal wire; a firstencapsulating step of encapsulating the first recess hole and part ofthe fine metal wire in a first transparent resin by a potting process soas to cover the LED chip; and a second encapsulating step ofencapsulating the first transparent resin in a second transparent resinby a transfer molding process so as to cover the first transparentresin.

That is, according to the manufacturing method of the present invention,it is unnecessary to form a wiring pattern and the like in the outerperiphery of the insulating substrate, which makes the manufacturingmethod easy and can reduce the manufacturing cost. When the first andsecond recess holes are formed by irradiating laser light to an LED chipmounting portion of the insulating substrate and removing the targetarea of the insulating substrate with the laser light such that thefirst and second recess holes reach the metal sheet of the undersurface,for example, because the laser light removes the insulating portionoutwardly from the center portion, the inner surfaces of the first andsecond recess holes can be formed to have inclined surfaces (curvedsurfaces). In other words, by only irradiating laser light, theformation of the first and second recess holes and the formation of theinclined inner surfaces can be performed at the same time.

Furthermore, according to the manufacturing method of the presentinvention, the second encapsulating step may involve encapsulating thesecond recess hole and part of the fine metal wire. It is also possibleto configure such that the manufacturing met hod of the presentinvention further involves a third encapsulating step of encapsulatingthe second recess hole and part of the fine metal wire in a thirdtransparent resin so as to cover the second recess hole, and in thesecond encapsulating step, the first transparent resin and the thirdtransparent resin are covered with the second transparent resin. It isalso possible to configure such that, in the second encapsulating step,the surface of the insulating substrate is covered with the secondtransparent resin. By covering the surface of the insulating substratewith the second transparent resin as described above, the conductivelayer formed on the substrate surface can be protected. It is alsopossible to configure such that, in the second encapsulating step, thesecond recess hole is not covered with the second transparent resin.

It is preferable that the first transparent resin is formed by a pottingprocess, and the second transparent resin is formed by a transfermolding process. That is, because it is difficult for the fluorescentmaterial to spread uniformly in the first recess hole in which the LEDchip has been mounted, it is preferable to form the first transparentresin by a potting process. Also, by forming the second transparentresin using a transfer molding process which allows en blocencapsulation, a reduction in the production cost can be achieved andpackages with uniform properties can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a chip-type LED according toEmbodiment 1 of the present invention.

FIG. 2( a) is a diagram illustrating a method for manufacturing thechip-type LED according to Embodiment 1 of the present invention.

FIG. 2( b) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 1 of the present invention.

FIG. 2( c) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 1 of the present invention.

FIG. 2( d) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 1 of the present invention.

FIG. 2( e) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 1 of the present invention.

FIG. 2( f) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 1 of the present invention.

FIG. 2( g) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 1 of the present invention.

FIG. 2( h) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 1 of the present invention.

FIG. 3 is a cross-sectional view of a chip-type LED according toVariation 1 of Embodiment 1 of the present invention.

FIG. 4 is a cross-sectional view of a chip-type LED according toVariation 2 of Embodiment 1 of the present invention.

FIG. 5 is a cross-sectional view of a chip-type LED according toVariation 3 of Embodiment 1 of the present invention.

FIG. 6 is a cross-sectional view of a chip-type LED according toEmbodiment 2 of the present invention.

FIG. 7( a) is a diagram illustrating a method for manufacturing thechip-type LED according to Embodiment 2 of the present invention.

FIG. 7( b) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 2 of the present invention.

FIG. 7( c) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 2 of the present invention.

FIG. 7( d) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 2 of the present invention.

FIG. 7( e) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 2 of the present invention.

FIG. 7( f) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 2 of the present invention.

FIG. 7( g) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 2 of the present invention.

FIG. 7( h) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 2 of the present invention.

FIG. 8 is a cross-sectional view of a chip-type LED according toEmbodiment 3 of the present invention.

FIG. 9 is a plan view of the chip-type LED according to Embodiment 3 ofthe present invention.

FIG. 10( a) is a diagram illustrating a method for manufacturing thechip-type LED according to Embodiment 3 of the present invention.

FIG. 10( b) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 3 of the present invention.

FIG. 10( c) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 3 of the present invention.

FIG. 10( d) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 3 of the present invention.

FIG. 10( e) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 3 of the present invention.

FIG. 10( f) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 3 of the present invention.

FIG. 10( g) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 3 of the present invention.

FIG. 10( h) is a diagram illustrating the method for manufacturing thechip-type LED according to Embodiment 3 of the present invention.

FIG. 11 is a cross-sectional view showing the structure of a chip-typeLED according to Variation 1 of Embodiment 3 of the present invention.

FIG. 12 is a cross-sectional view showing an example of the structure ofa conventional chip-type LED.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to the accompanying drawings.

Embodiment 1

FIG. 1 is a cross-sectional view of a chip-type LED 10 according toEmbodiment 1 of the present invention.

In the chip-type LED 10, a first recess hole (through hole) 3 a formounting an LED chip and a second recess hole (through hole) 3 b forconnecting a fine metal wire are formed in an insulating substrate 1.Metal (Cu) sheets 2 a and 2 b serving as the wiring patterns for therecess holes are formed on the undersurface side of the insulatingsubstrate 1 in an electrically insulated state. On the surface side ofthe insulating substrate 1, a metal sheet 4 a serving as a first wiringpattern is formed in a portion that includes the first recess hole 3 a,and a metal sheet 4 b serving as a second wiring pattern is formed in aportion that includes the second recess hole 3 b. In this wiringstructure, an LED chip 5 is mounted on the metal sheet 4 a at the bottomportion of the first recess hole 3 a, and the LED chip 5 is electricallyconnected to the metal sheet 4 b at the bottom portion of the secondrecess hole 3 b via a fine metal wire 6. In this state, the entiresurface of the insulating substrate 1, including the LED chip 5 and thefine metal wire 6, is encapsulated in a transparent resin 7.

In Embodiment 1, the transparent resin 7 is formed of a firsttransparent resin 71 for encapsulating the LED chip 5 including thefirst recess hole 3 a and the entire fine metal wire 6 including thesecond recess hole 3 b; and a second transparent resin 72 forencapsulating the entire surface of the insulating substrate 1 includingthe first transparent resin 71. Although the details will be given laterwhen describing a method of manufacture thereof, the first transparentresin 71 contains a yellow fluorescent material (e.g., α-SIALON, etc.)and is formed by potting. The second transparent resin 72 is made ofonly a transparent resin and is formed by transfer molding. The reasonfor adopting such configuration and manufacturing method is to avoiduneven distribution of the fluorescent material, which is a disadvantageof transfer molding. The layer that contains a fluorescent material isformed by potting, and the outer shape of the transparent resin 7, whichaffects extraction of light, that is, the outer shape of the secondtransparent resin is formed by transfer molding in which molding can beperformed stably.

In Embodiment 1, the first transparent resin 71 is made of asilicone-based resin, and the second transparent resin 72 is made of anepoxy-based resin. The insulating substrate 1 is formed of a glass epoxyresin and has a thickness of approximately 50 μm. The metal (Cu) sheets2 a and 2 b formed on the undersurface side are formed to have athickness of approximately 20 μm. Furthermore, in the presentembodiment, the first recess hole 3 a for mounting an LED chip is formedto have an inner diameter φ of 470 μm, and the second recess hole 3 bfor connecting a fine metal wire is formed to have an inner diameter φof 180 μm.

As described above, according to Embodiment 1, because the area on whichthe LED chip 5 is mounted and the area to which an end of the fine metalwire 6, the other end of which is connected to the LED chip 5, isconnected are formed on the metal sheets 2 a and 2 b, the height of thefine metal wire 6 can be lowered. In addition, because the LED chip 5 ismounted directly on the metal sheets 4 a and 2 a, it is unnecessary touse a conventional substrate, so the thickness can be reduced and theheight of the fine metal wire 6 can be made lower than that ofconventional technology, making the chip-type LED even thinner.

A method for manufacturing the chip-type LED 10 thus configured will bedescribed with reference to FIGS. 2( a) to 2(h).

In the first step, metal sheets 2 and 4 are formed on the surface andundersurface of an insulating substrate 1, respectively (FIG. 2( a)).

In the next step, the metal sheet 4 is removed at an LED chip mountingposition 41 and a fine metal wire connecting position 42 on the surfaceside of the insulating substrate 1 (FIG. 2( b)).

In the next step, recess holes 3 a and 3 b having inclined surfaces areformed by a laser process in the regions 41 and 42, from which the metalsheet 4 has been removed, such that the recess holes 3 a and 3 b have adepth extending to the metal sheet 2 on the undersurface side of theinsulating substrate 1 (FIG. 2( c)). In Embodiment 1, the first recesshole 3 a for mounting an LED chip is formed to have an inner diameter φof 470 μm, and the second recess hole 3 b for connecting a fine metalwire is formed to have an inner diameter φ of 180 μm.

In the next step, a 20 μm thick Cu plating layer 45 is formed by platingon the surface side of the insulating substrate 1 such that the platinglayer 45 extends over the side faces of the recess holes 3 a and 3 b andthe metal sheet 2 at the bottom of the recess holes 3 a and 3 b (FIG. 2(d)). In this process, a resist is used to protect areas on which the Cuplating is unnecessary.

In the next step, a 10 μm thick Ni/Au layer is formed on the surface ofthe plating layer 45 by vapor deposition to protect the surface fromrust caused by moisture, oxidation, etc.

In the next step, in order to form insulating regions, an unnecessaryportion of the Ni/Au layer, Cu plate layer 45 and metal sheet 4 on thesurface of the insulating substrate 1 is removed (indicated by referencenumeral 46). At the same time, an unnecessary portion of the metal sheet2 on the undersurface of the insulating substrate 1 is also removed(indicated by reference numeral 22) (FIG. 2( e)). In this manner, ametal sheet 4 a serving as a first wiring pattern and a metal sheet 4 bserving as a second wiring pattern are formed on the surface of theinsulating substrate 1 in an insulated state. Likewise, a metal sheet 2a facing the metal sheet 4 a as the first wiring pattern and a metalsheet 2 b facing the metal sheet 4 b as the second wiring pattern areformed on the undersurface of the insulating substrate 1 in an insulatedstate.

In the next step, an LED chip 5 is mounted on the metal sheet 4 a at thebottom of the recess hole 3 a for mounting an LED chip, using a silverpaste (FIG. 2( f)).

In the next step, the mounted LED chip 5 and the metal sheet 4 b at thebottom of the recess hole 3 b for connecting a fine metal wire areelectrically connected by bonding using a fine metal wire 6 (FIG. 2(g)).

In the next step, the entire surface of the insulating substrate 1,including the LED chip 5 and the fine metal wire 6, is encapsulated in atransparent resin (FIG. 2( h)). Specifically, the LED chip 5 includingthe first recess hole 3 a and the entire fine metal wire 6 including thesecond recess hole 3 b are encapsulated by a potting process using asilicone-based resin that contains a fluorescent material, forming afirst transparent resin 71. Then, the entire surface of the insulatingsubstrate 1, including the first transparent resin 71, is encapsulatedby a transfer molding process using an epoxy-based resin that containsno fluorescent material, forming a second transparent resin 72. Here,the conditions for curing the first transparent resin 71 in the pottingprocess and the second transparent resin 72 in the transfer moldingprocess are set at 150° C. for one hour.

The reason for using a silicone resin for the first transparent resin 71is to suppress to a minimum possible the degradation caused by lightdirectly emitted from the chip before conversion by the fluorescentmaterial into longer wavelength light. Likewise, the reason for using anepoxy resin for the second transparent resin is to stabilize the outershape with its high rigidity.

Although the wiring patterns (Cu) provided in the insulating substrateare protected by the Ni/Au layer, in order to increase lightreflectivity, the surface of the insulating substrate may be plated withAg so as to at least include the first and second recess holes. In thiscase, it is preferable that the entire surface of the insulatingsubstrate is covered with the second transparent resin. By using a resinhaving a gas blocking property and low hygroscopicity, such as an epoxyresin, as the second transparent resin, it is possible to protect the Agplating from corrosion.

Finally, dicing is performed to obtain a pseudo-white light emittingchip-type LED 10 (see FIG. 1) having a width of 1.6 mm, a thickness of0.8 mm and a height of 0.2 mm.

In the present embodiment, a yellow fluorescent material is added to thefirst transparent resin 71, but it is also possible to add a redfluorescent material or green fluorescent material instead of a yellowfluorescent material. When a red or green fluorescent material is added,high color-rendering white light whose color rendering property isimproved as compared to pseudo-white light can be emitted. This appliesto the embodiments given hereunder.

Variation 1 of Embodiment 1

FIG. 3 is a cross-sectional view showing the structure of a chip-typeLED 10 according to Variation 1 of Embodiment 1.

Variation 1 employs a structure in which the first transparent resin 71is formed to include only the entire first recess hole 3 a, includingthe LED chip 5 and part of the fine metal wire 6 connected to the LEDchip 5, and the periphery of the hole, and not to include the secondrecess hole 3 b. The first transparent resin 71 is formed using asilicone-based resin containing a yellow fluorescent material, and thesecond transparent resin 72 is formed using an epoxy-based resincontaining no fluorescent material. Other elements are the same as thoseof the chip-type LED 10 of Embodiment 1 shown in FIG. 1, and thus adescription thereof is omitted here. Similarly, a manufacturing methodthereof is the same as the manufacturing method described with referenceto FIGS. 2( a) to 2(h), and thus a description thereof is omitted here.

Variation 2 of Embodiment 1

FIG. 4 is a cross-sectional view showing the structure of a chip-typeLED 10 according to Variation 2 of Embodiment 1.

Variation 2 employs a structure in which the LED chip 5 including thefirst recess hole 3 a and part of the fine metal wire 6 are encapsulatedin the first transparent resin 71 containing a yellow fluorescentmaterial, the second recess hole 3 b and another part of the fine metalwire 6 are encapsulated in a third transparent resin 73, and the entiresurface of the insulating substrate 1, including the first transparentresin 71 and the third transparent resin 73, is encapsulated in thesecond transparent resin 72. In Variation 2, the first transparent resin71 is made of a silicone-based resin, the second transparent resin 72 ismade of an epoxy-based resin, and the third transparent resin 73 is madeof a silicone-based resin. By forming the third transparent resin 73with a silicone-based resin, it is possible to reduce the occurrence ofa disconnection defect in the connecting portion of the fine metal wire6 because silicone-based resins have a small thermal expansioncoefficient. Furthermore, in Variation 2, because differentencapsulating resins can be used for the first recess hole 3 a formounting an LED chip, the second recess hole 3 b for connecting a finemetal wire and other regions of the insulating substrate surface, it ispossible to form a package structure that can provide a great freedom inselection of resins.

In Variation 2, the step of encapsulating the entire surface of theinsulating substrate 1, including the LED chip 5 and the fine metal wire6, in transparent resins is different from that of the manufacturingmethod described above with reference to FIGS. 2( a) to 2(h).Accordingly, only different steps will be described here.

Specifically, the LED chip 5 including the first recess hole 3 a andpart of the fine metal wire 6 are encapsulated by a potting processusing a silicone-based resin that contains a fluorescent material,forming a first transparent resin 71. Then, the second recess hole 3 band another part of the fine metal wire 6 are encapsulated by a pottingprocess using a silicone-based resin, forming a third transparent resin73. After that, the entire surface of the insulating substrate 1,including the first transparent resin 71 and the third transparent resin73, is encapsulated by a transfer molding process using an epoxy-basedresin to form a second transparent resin 72. Here, the conditions forcuring the first transparent resin 71 and the third transparent resin 73in the potting process and the second transparent resin 72 in thetransfer molding process are set at 150° C. for one hour.

Variation 3 of Embodiment 1

FIG. 5 is a cross-sectional view showing the structure of a chip-typeLED 10 according to Variation 3 of Embodiment 1.

Variation 3 employs a structure in which the second transparent resin 72is formed to include the entire first transparent resin 71, the entirefirst recess hole 3 a and the periphery of the hole, and not to includethe second recess hole 3 b. Other elements are the same as those of thechip-type LED 10 according to Variation 1 of Embodiment 1 shown in FIG.3, and thus a description thereof is omitted here. Similarly, amanufacturing method thereof is the same as the manufacturing methoddescribed with reference to FIGS. 2( a) to 2(h), and thus a descriptionthereof is omitted here.

Embodiment 2

FIG. 6 is a cross-sectional view showing the structure of a chip-typeLED 20 according to Embodiment 2. In the description given below, thesame reference numerals are assigned to components that are the same (orhave the same functions) as those of Embodiment 1 described above.

In the chip-type LED 20, a first recess hole (through hole) 3 a formounting an LED chip is formed in an insulating substrate 1. A secondrecess hole (through hole) 3 b and a third recess hole (through hole) 3c both for connecting a fine metal wire are formed on opposite sides ofthe first recess hole 3 a so as to sandwich the first recess hole 3 a.Metal (Cu) sheets 2 a, 2 b and 2 c serving as the wiring patterns forthe recess holes are formed on the undersurface of the insulatingsubstrate 1 in an electrically insulated state. On the surface side ofthe insulating substrate 1, a metal sheet 4 a serving as a first wiringpattern is formed in a portion that includes the first recess hole 3 a,a metal sheet 4 b serving as a second wiring pattern is formed in aportion that includes the second recess hole 3 b, and a metal sheet 4 cserving as a third wiring pattern is formed in a portion that includesthe third recess hole 3 c. In this wiring structure, an LED chip 5 ismounted on the metal sheet 4 a at the bottom portion of the first recesshole 3 a. The LED chip 5 is electrically connected to the metal sheet 4b at the bottom portion of the second recess hole 3 b via a fine metalwire 6 a and also to the metal sheet 4 c at the bottom portion of thethird recess hole 3 c via a fine metal wire 6 b. In this state, theentire surface of the insulating substrate 1, including the LED chip 5and the fine metal wires 6 a and 6 b, is encapsulated in a transparentresin 7.

In Embodiment 2, the transparent resin 7 is formed of: a firsttransparent resin 71 for encapsulating the LED chip 5 including thefirst recess hole 3 a, the fine metal wire 6 a including the secondrecess hole 3 b and the fine metal wire 6 b including the third recesshole 3 c; and a second transparent resin 72 for encapsulating the entiresurface of the insulating substrate 1 including the first transparentresin 71. In Embodiment 2, the first transparent resin 71 is made of asilicone-based resin that contains a yellow fluorescent material, andthe second transparent resin 72 is made of an epoxy-based resin thatcontains no fluorescent material. The insulating substrate 1 is formedof a glass epoxy resin and has a thickness of approximately 60 μm. Themetal (Cu) sheets 2 a and 2 b formed on the undersurface side are formedto have a thickness of approximately 25 μm. Furthermore, in Embodiment2, the first recess hole 3 a for mounting an LED chip is formed to havean inner diameter φ of 500 μm, and the second recess hole 3 b and thirdrecess hole 3 c for connecting a fine metal wire are formed to have aninner diameter φ of 200 μm.

As described above, according to Embodiment 2, because the area on whichthe LED chip 5 is mounted and the areas to which ends of the fine metalwires 6 a and 6 b, the other ends of which are connected to the LED chip5, are connected are formed on the metal sheets 2 a, 2 b and 2 c, theheight at which the fine metal wires 6 a and 6 b are disposed can belowered. In addition, because the LED chip 5 is mounted directly on themetal sheets 4 a and 2 a, it is unnecessary to use a conventionalsubstrate, so the thickness can be reduced and the height of the finemetal wires 6 a and 6 b can be made lower than that of conventionaltechnology, making the chip-type LED even thinner.

A method for manufacturing the chip-type LED 20 thus configured will bedescribed with reference to FIGS. 7( a) to 7(h).

In the first step, metal sheets 2 and 4 are formed on the surface andundersurface of an insulating substrate 1, respectively (FIG. 7( a)).

In the next step, the metal sheet 4 is removed at an LED chip mountingposition 41 and fine metal wire connecting positions 42 and 43 on thesurface side of the insulating substrate 1 (FIG. 7( b)).

In the next step, recess holes 3 a, 3 b and 3 c having inclined surfacesare formed by a laser process in the regions 41, 42 and 43, from whichthe metal sheet 4 has been removed, such that the recess holes 3 a, 3 band 3 c have a depth extending to the metal sheet 2 on the undersurfaceside of the insulating substrate 1 (FIG. 7( c)). In Embodiment 2, thefirst recess hole 3 a for mounting an LED chip is formed to have aninner diameter φ of 500 μm and the second recess hole 3 b and thirdrecess hole 3 c for connecting a fine metal wire are formed to have aninner diameter φ of 200 μm.

In the next step, a 15 μm thick Cu plating layer 45 is formed by platingon the surface side of the insulating substrate 1 such that the platinglayer 45 extends over the side faces of the recess holes 3 a, 3 b and 3c and the metal sheet 2 at the bottom of the recess holes 3 a, 3 b and 3c (FIG. 7( d)). In this process, a resist is used to protect areas onwhich the Cu plating is unnecessary.

In the next step, a 15 μm thick Ni/Au layer is formed on the surface ofthe plating layer 45 by vapor deposition.

In the next step, in order to form insulating regions, unnecessaryportions of the Ni/Au layer, Cu plating layer 45 and metal sheet 4 onthe surface of the insulating substrate 1 are removed (indicated byreference numerals 46 and 47). At the same time, unnecessary portions ofthe metal sheet 2 on the undersurface of the insulating substrate 1 arealso removed (indicated by reference numerals 22 and 23) (FIG. 7( e)).In this manner, a metal sheet 4 a serving as a first wiring pattern, ametal sheet 4 b serving as a second wiring pattern and a metal sheet 4 cserving as a third wiring pattern are formed on the surface of theinsulating substrate 1 in an insulated state. Likewise, a metal sheet 2a facing the metal sheet 4 a as the first wiring pattern, a metal sheet2 b facing the metal sheet 4 b as the second wiring pattern and a metalsheet 2 c facing the metal sheet 4 c as the third wiring pattern areformed on the undersurface of the insulating substrate 1 in an insulatedstate.

In the next step, an LED chip 5 is mounted on the metal sheet 4 a at thebottom of the recess hole 3 a for mounting an LED chip, using a siliconeresin (FIG. 7( f)).

In the next step, the mounted LED chip 5 and the metal sheet 4 b at thebottom of the recess hole 3 b for connecting a fine metal wire areelectrically connected by bonding using a fine metal wire 6 a. At thesame time, the mounted LED chip 5 and the metal sheet 4 c at the bottomof the recess hole 3 c for connecting a fine metal wire are electricallyconnected by bonding using a fine metal wire 6 b (FIG. 7( g)).

In the next step, the entire surface of the insulating substrate 1,including the LED chip 5 and the fine metal wires 6 a and 6 b, isencapsulated in a transparent resin (FIG. 7( h)). Specifically, the LEDchip 5 including the first recess hole 3 a and the entire fine metalwires 6 a and 6 b including the second recess hole 3 b and the thirdrecess hole 3 c are encapsulated by a potting process using asilicone-based resin that contains a fluorescent material, forming afirst transparent resin 71. Then, the entire surface of the insulatingsubstrate 1 including the first transparent resin 71 is encapsulated bya transfer molding process using an epoxy-based resin that contains nofluorescent material, forming a second transparent resin 72. Here, theconditions for curing the first transparent resin 71 in the pottingprocess are set at 150° C. for three hours, and the conditions forcuring the second transparent resin 72 in the transfer molding processare set at 120° C. for one hour.

Finally, dicing is performed to obtain a blue light emitting chip-typeLED 20 having a width of 1.5 mm, a thickness of 0.8 mm and a height of0.18 mm (see FIGS. 7( a) to 7(h)).

Embodiment 3

FIGS. 8 and 9 are a cross-sectional view and a plan view of a chip-typeLED 30 according to Embodiment 3. In the description given below, thesame reference numerals are assigned to components that are the same (orhave the same functions) as those of Embodiment 1 described above.

In the chip-type LED 30, a first recess hole (through hole) 3 a formounting an LED chip and a second recess hole (through hole) 3 b forconnecting a fine metal wire are formed in an insulating substrate 1.Metal (Cu) sheets 2 a and 2 b serving as the wiring patterns for therecess holes are formed on the undersurface side of the insulatingsubstrate 1 in an electrically insulated state. On the surface side ofthe insulating substrate 1, a metal sheet 4 a serving as a first wiringpattern is formed in a portion that includes the first recess hole 3 a,and a metal sheet 4 b serving as a second wiring pattern is formed in aportion that includes the second recess hole 3 b. The metal sheets 4 aand 4 b are insulated from each other by a cut-off portion 48 that has apredetermined width and is formed in the center portion of the surfaceof a partition wall 1 a for separating the first recess hole 3 a and thesecond recess hole 3 b from each other, by removing the metal sheet 4. Arecess groove 11 having a predetermined depth is formed on the surfaceof the partition wall 1 a in a direction perpendicular to the cut-offportion 48, or in other words, such that the recess groove 11 connectsthe first recess hole 3 a and the second recess hole 3 b.

In this wiring structure, an LED chip 5 is mounted on the metal sheet 4a at the bottom portion of the first recess hole 3 a, and the LED chip 5is electrically connected to the metal sheet 4 b at the bottom portionof the second recess hole 3 b via a fine metal wire 6. The fine metalwire 6 is provided such that it passes through the inside of the recessgroove 11 of the partition wall 1 a. In other words, the fine metal wire6 is provided such that it does not appear above the surface of theinsulating substrate 1. In this state, the entire surface of theinsulating substrate 1, including the LED chip 5 and the fine metal wire6, is encapsulated in a transparent resin 7.

In Embodiment 3, the transparent resin 7 is formed of a firsttransparent resin 71 for encapsulating the LED chip 5 including thefirst recess hole 3 a and the entire fine metal wire 6 including thesecond recess hole 3 b; and a second transparent resin 72 forencapsulating the entire surface of the insulating substrate 1 includingthe first transparent resin 71. In Embodiment 3, the first transparentresin 71 is made of a silicone-based transparent resin that contains afluorescent material (e.g., CaAlSiN₃:Eu, Ca₃(Sc.Mg)₂Si₃O₁₂:Ce, etc.).The second transparent resin 72 is formed of an epoxy-based transparentresin that contains no fluorescent material.

In Embodiment 3, the insulating substrate 1 is formed of a glass epoxyresin and has a thickness of approximately 55 μm. The metal (Cu) sheets2 a and 2 b formed on the undersurface side are formed to have athickness of approximately 18 μm. In Embodiment 3, the first recess hole3 a for mounting an LED chip is formed to have an inner diameter φ of400 μm, and the second recess hole 3 b for connecting a fine metal wireis formed to have an inner diameter φ of 150 μm. The recess groove 11 isformed to have a depth of 25 μm.

As described above, according to Embodiment 3, because the area on whichthe LED chip 5 is mounted and the area to which an end of the fine metalwire 6, the other end of which is connected to the LED chip 5, isconnected are formed on the metal sheets 2 a and 2 b, and the fine metalwire 6 is passed through the inside of the recess groove 11, it ispossible to lower the height of the fine metal wire 6 even more thanwith Embodiments 1 and 2. In addition, because the LED chip 5 is mounteddirectly on the metal sheets 4 a and 2 a, it is unnecessary to use aconventional substrate, so the thickness can be reduced.

A method for manufacturing the chip-type LED 30 thus configured will bedescribed with reference to FIGS. 10( a) to 10(h).

In the first step, metal sheets 2 and 4 are formed on the surface andundersurface of an insulating substrate 1, respectively (FIG. 10( a)).

In the next step, the metal sheet 4 is removed at an LED chip mountingposition 41, a fine metal wire connecting position 42 and a wiringposition (the position at which a recess groove 11 is formed) for a finemetal wire 6 on the surface side of the insulating substrate 1 (FIG. 10(b)).

In the next step, recess holes 3 a and 3 b having inclined surfaces areformed by a laser process in the regions 41 and 42, from which the metalsheet 4 has been removed, such that the recess holes 3 a and 3 b have adepth extending to the metal sheet 2 on the undersurface side of theinsulating substrate 1. At this time, a recess groove 11 having apredetermined depth is formed also by the same laser process on thesurface of the partition wall 1 a for separating recess holes 3 a and 3b to be formed such that the recess groove 11 connects the recess holes3 a and 3 b (FIG. 10( c),FIG. 8,FIG. 9). In Embodiment 3, the firstrecess hole 3 a for mounting an LED chip is formed to have an innerdiameter φ of 500 μm, the second recess hole 3 b for connecting a finemetal wire is formed to have an inner diameter φ of 200 μm, and therecess groove 11 is formed to have a depth of 25 μm.

In the next step, a 25 μm thick Cu plating layer 45 is formed by platingon the surface side of the insulating substrate 1 such that the platinglayer 45 extends over the side faces of the recess holes 3 a and 3 b andthe metal sheet 2 at the bottom of the recess holes 3 a and 3 b (FIG.10( d)). In this process, a resist is used to protect areas on which theCu plating is unnecessary.

In the next step, a 10 μm thick Ni/Au layer is formed on the surface ofthe plating layer 45 by vapor deposition.

In the next step, in order to form insulating regions, an unnecessaryportion of the Ni/Au layer, Cu plate layer 45 and metal sheet 4 on thesurface of the insulating substrate 1 is removed (indicated by referencenumeral 46). At the same time, an unnecessary portion of the metal sheet2 on the undersurface of the insulating substrate 1 is also removed(indicated by reference numeral 22) (FIG. 10( e)). In this manner, ametal sheet 4 a serving as a first wiring pattern and a metal sheet 4 bserving as a second wiring pattern are formed on the surface of theinsulating substrate 1 in an insulated state. Likewise, a metal sheet 2a facing the metal sheet 4 a as the first wiring pattern and a metalsheet 2 b facing the metal sheet 4 b as the second wiring pattern areformed on the undersurface of the insulating substrate 1 in an insulatedstate. In this step of Embodiment 3, the Ni/Au layer and Cu platinglayer 45 are removed at the surface of the recess groove 11 in which afine metal wire 6 is to be provided. That is, the insulating substrate 1is exposed at the surface of the recess groove 11.

In the next step, an LED chip 5 is mounted on the metal sheet 4 a at thebottom of the recess hole 3 a for mounting an LED chip using an epoxyresin (FIG. 10( f).

In the next step, the mounted LED chip 5 and the metal sheet 4 b at thebottom of the recess hole 3 b for connecting a fine metal wire areelectrically connected by bonding using a fine metal wire 6 (FIG. 10(g)).

In the next step, the entire surface of the insulating substrate 1,including the LED chip 5 and the fine metal wire 6, is encapsulated in atransparent resin (FIG. 10( h)). Specifically, the LED chip 5 includingthe first recess hole 3 a, the fine metal wire 6 including the secondrecess hole 3 b and the recess groove 11 for communicating the recessholes 3 a and 3 b are all encapsulated by a potting process using asilicone-based resin that contains a fluorescent material (CaAlSiN₃:Eu,Ca₃(Sc.Mg)₂Si₃O₁₂:Ce), forming a first transparent resin 71. Then, theentire surface of the insulating substrate 1 including the firsttransparent resin 71 is encapsulated by a transfer molding process usingan epoxy-based resin that contains no fluorescent material, forming asecond transparent resin 72. Here, the conditions for curing the firsttransparent resin 71 in the potting process are set at 150° C. for onehour, and the conditions for curing the second transparent resin 72 inthe transfer molding process is set at 150° C. for three hours.

Finally, dicing is performed to obtain a high color-rendering chip-typeLED 30 (see FIG. 8) having a width of 1.65 mm, a thickness of 0.75 mmand a height of 0.15 mm.

According to Embodiment 3, because the fine metal wire 6 can be passedthrough the inside of the recess groove 11 formed between the recesshole 3 a for mounting an LED chip and the recess hole 3 b for connectinga fine metal wire, it is possible to produce a chip-type LED 30 havingan even lower height of 0.15 mm.

Variation 1 of Embodiment 3

FIG. 11 is a cross-sectional view showing the structure of a chip-typeLED 30 according to Variation 1 of Embodiment 3.

Variation 1 of Embodiment 3 employs a structure in which the firsttransparent resin 71 is formed to include only the entire first recesshole 3 a, including the LED chip 5 and part of the fine metal wire 6connected to the LED chip 5, and the periphery of the hole, and not toinclude the second recess hole 3 b. Other elements are the same as thoseof the chip-type LED 10 of Embodiment 3 shown in FIG. 8, and thus adescription thereof is omitted here. Similarly, a manufacturing methodthereof is the same as the manufacturing method of Embodiment 3described with reference to FIGS. 10( a) to 10(h), and thus adescription thereof is omitted here.

Embodiments 1 to 3 given above are discussed in the context of asingle-chip LED lamp that includes a pair of patterns on an insulatingsubstrate, but it is also possible to configure a multicolor lightemitting LED lamp (having a plurality of LED chips) easily by forming aplurality of patterns using the same procedure and connecting aplurality of LED chips. As the LED chip 5, it is possible to use, inaddition to a blue light emitting LED chip, LED chips such as red,yellow and green LED chips can be used.

In the present application, the invention that emits white light hasbeen described, but by selecting an LED chip that emits light having awavelength within the range from ultraviolet to blue light and choosinga fluorescent material capable of emitting light of a desired colorwithin the range from blue to red visible light under excitation by theLED chip, it is possible to provide a chip-type LED capable of emittinga desired visible light. For example, if a blue light emitting LED chipand a red fluorescent material, namely CaAlSiN₃:Eu, are selected, amonochromatic light source capable of emitting red light is obtained.

The present invention may be embodied in various other forms withoutdeparting from the gist or essential characteristics thereof. Theembodiments disclosed in this application are to be considered in allrespects as illustrative and not limiting. The scope of the invention isindicated by the appended claims rather than by the foregoingdescription, and all modifications or changes that come within themeaning and range of equivalency of the claims are intended to beembraced therein.

1. A chip-type LED, comprising: an insulating substrate; a first recess hole for mounting an LED chip formed in the insulating substrate; a second recess hole for connecting a fine metal wire formed in the insulating substrate; a metal sheet serving as a first wiring pattern is formed at a portion of the chip-type LED that includes the first recess hole; a metal sheet serving as a second wiring pattern is formed at a portion of the chip-type LED that includes the second recess hole; and an LED chip is mounted on the metal sheet within the first recess hole, the LED chip is being electrically connected to the metal sheet within the second recess hole via a fine metal wire, wherein the LED chip including the first recess hole and the entire fine metal wire including the second recess hole are encapsulated in a first transparent resin that contains a fluorescent material, and a surface of the insulating substrate including the first transparent resin is encapsulated in a second transparent resin.
 2. The chip-type LED according to claim 1, wherein an encapsulation with the first transparent resin is performed by a process different from that with the second transparent resin.
 3. The chip-type LED according to claim 1, wherein the first transparent resin is a silicone-based resin, and the second transparent resin is an epoxy-based resin.
 4. The chip-type LED according to claim 1, wherein the bottom of the first recess hole on which the LED chip is mounted and the bottom of the second recess hole to which the fine metal wire extending from the LED chip is electrically connected are formed to have a substantially equal height.
 5. The chip-type LED according to claim 1, wherein the second recess hole to which the fine metal wire extending from the LED chip is electrically connected is formed at least two locations.
 6. The chip-type LED according to claim 1, wherein a groove in which the fine metal wire is provided is formed on the surface of a wall member provided between the first recess hole and the second recess hole.
 7. The chip-type LED according to claim 1, wherein the inner surfaces of the recess holes are formed to have inclined surfaces that flare gradually from the undersurface toward the surface of the insulating substrate. 